Production on the big-screen adaptation of John Green's "The Fault in Our Stars" may have begun a little more than a week ago, but Shailene Woodley and Ansel Elgort's co-star Nat Wolff is just now stepping in front of the camera. The actor took to Twitter today to share a first-day selfie.

Nat, who originally auditioned for the role of Augustus Waters, is playing Isaac, Gus' buddy and fellow Cancer Kid Support Group member. (He's most likely wearing shades in the snap because his character lost an eye to cancer at a young age.)